Method of activating alpha-amylase

ABSTRACT

The invention provides an activation method of α-amylase. α-Amylase or particles containing the same are contacted with an oxidizing agent or particles containing the same. After contacting, the activated α-amylase can be separated from the oxidizing agent. After contacting, α-amylase and the oxidizing agent can be incorporated in the form of a mixture into a detergent base to give a detergent composition.

FIELD OF THE INVENTION

The present invention relates to a method of activating α-amylase and toα-amylase activated by the method.

BACKGROUND OF THE INVENTION

α-Amylase (1,4-α-D-glucan glucanohydrolase [EC3.2.1.1]) is an endo-typeenzyme which randomly cleaves α-1,4 glucoside linkages of starch,glycogen etc. This enzyme is widely used industrially in starchprocessing, food processing, fiber processing, fermentation,pharmaceutical preparations, clinical examination and detergents, and isderived from a wide variety of sources such as microorganisms, plantsand animals.

Conventionally, this industrially very important enzyme is not alwayssatisfactory in respect of its activity and cost, and as a means forsolving this problem, an increase in productivity of the enzyme andreinforcement of the catalytic ability of the enzyme have been attemptedby genetic recombination and protein engineering technology, and amethod of improving the reaction rate of the enzyme in an enzymereaction system, that is, a method of activating the enzyme reaction,has been examined.

With respect to the method of activating the enzyme, there are reportson activation by adding a specific polymer to an enzyme reaction system(JP-A(W) 5-507615), activation by adding chlorine ions to specificamylase (Clin. Biochem., 16, 224-228 (1983)), the enhancement of theenzyme activity by utilizing a reverse phase micelle system obtained byadding Tween 20 (polyoxyethylene sorbitan monolaurate) to n-hexane(Biotechnol. Bioeng., 29, 901-902 (1987)), and the enhancement of theenzyme activity by adding an alkyl sulfate and/or alkyl sulfonate havingan alkyl group of specific length to an enzyme reaction system (JP-A8-256768). Further, a method of activating the enzyme in a step prior tothe enzyme reaction by previously dissolving the enzyme in electrolyticwater (JP-A 2000-245453) and a method of activating the enzyme bydissolving the enzyme in an exothermic inorganic salt (JP-A 2000-37186)have been reported.

With respect to the method of producing a detergent compositioncontaining the enzyme, many literatures have reported separateafter-blending of the enzyme, a bleaching agent etc. into a detergentbase obtained by various granulation procedures.

DISCLOSURE OF THE INVENTION

The invention provides a method of activating α-amylase, which includesa step of contacting A) α-amylase or particles containing α-amylase withB) an oxidizing agent or particles containing an oxidizing agent.

The invention then provides a method of activating α-amylase, whichincludes steps of contacting A) α-amylase or particles containingα-amylase with B) an oxidizing agent or particles containing anoxidizing agent and separating A) α-amylase or particles containingα-amylase after the contacting step.

The invention then provides a method of producing activated α-amylase,which includes steps of contacting A) α-amylase or particles containingα-amylase with B) an oxidizing agent or particles containing anoxidizing agent and separating A) α-amylase or particles containingα-amylase after the contacting step.

The invention then provides α-Amylase which is obtainable by the aboveshown method and a detergent composition containing the α-amylase.

Moreover the invention provides a method of producing anα-amylase-containing detergent composition, which including a detergentbase with a mixed and treated material obtained by mixing A) α-amylaseor particles containing α-amylase with B) an oxidizing agent orparticles containing an oxidizing agent.

DETAILED EXPLANATION OF THE INVENTION

These activation methods can increase the rate of enzyme reaction to acertain degree, but cannot be said to be satisfactory in respect of theactivation power. These activation methods have a problem thatlarge-scale facilities are required for activation treatment of theenzyme in the form of a solution, and because separation of theactivator for enzyme reaction is difficult, the final product iscontaminated therewith to decrease its product value, and thereforethese methods are problematic for use as general-purpose techniques.

Under these circumstances, the present inventors made extensive study onthe method of activating α-amylase, and as a result, they found thatα-amylase can be significantly activated by contacting the α-amylase andan oxidizing agent with each other in solid forms, respectively, forpretreatment for enzyme reaction, and the present invention was therebycompleted.

The present invention provides an activation method of significantlyincreasing the enzyme activity of α-amylase by easy operation. Thepresent invention further provides a detergent composition containingα-amylase obtained by the activation method.

Hereinafter, the terms “α-amylase” and “oxidizing agent” may encompassα-amylase-containing particles and oxidizing agent-containing particles,respectively.

According to the present invention, activated α-amylase can be obtainedby an easy method. The oxidizing agent used in the contacting step canbe easily separated from the α-amylase, and the activated α-amylase withfewer impurities can be widely used as a component in various industrialprocesses and detergents. The α-amylase activated according to thepresent invention can greatly contribute to reduction in the amount ofthe enzyme used and to reduction in the reaction time. The oxidizingagent used in activation in the present invention can be repeatedlyused. Accordingly, the present invention also brings about anadvantageous effect in an economical aspect in the enzyme reaction usingα-amylase and its applied technology.

According to the present invention, α-amylase and the oxidizing agentcan be incorporated, in a mixed state without separation, into acomposition such as a detergent. This operation is particularlyeffective when the composition contains the oxidizing agent as an activeingredient. That is, the composition can be endowed with a higher enzymeeffect than by a conventional method of adding α-amylase and anoxidizing agent separately, while there is an advantage in process thatintroduction of α-amylase and the oxidizing agent can be simultaneouslycompleted.

With regard to the α-amylase as the subject of the present invention, itis possible to employ α-amylase obtained from many living creatures, forexample microorganisms such as Bacillus subtilis Marburg, Cacillussubtilis natto, Bacillus amyloliquefaciens, Bacillus licheniformis,Bacillus cereus, Bacillus macerans, Pseudomonas stutzeri, Klebusiellaaerogenes etc., actinomyces such as Streptomyces griseus etc., fungisuch as Aspergillus oryzae, Aspergillus niger etc., seeds of Gramineaeand Leguminosae plants, and digestive glands of animals such as humanand swine.

The α-amylase used in the present invention can be obtained byinoculating the above microorganism, a variant thereof, or a host celletc. transformed with a recombinant vector having a DNA sequenceencoding the enzyme or its variant onto a medium containing essentialnutrients such as assimilable carbon and nitrogen sources etc.,culturing it in a usual manner, and separating the formed enzyme byusual enzyme collection and purification methods. The enzyme solutionobtained in this manner can be used as such, or may be used afterfurther purification, crystallization, powdering or granulation by knownmethods (for example, JP-B 58-26315, JP-A (W) 7-500013, JP-A 62-255990,JP-A 9-48996).

The form of α-amylase used in the present invention includes (1) a driedproduct of the enzyme protein, (2) solids containing the enzyme protein,and (3) a liquid containing the enzyme protein, among which (1) and (2)are preferably used for the reason that after α-amylase is contactedwith an oxidizing agent or particles containing the same, these can beeasily separated from each other. When (1) or (2) is used, the averageparticle diameter thereof is preferably 20 to 4000 μm, more preferably250 to 1000 μm.

The average particle diameter can be determined by attaching a standardsieve according to JIS K 8801, having sieve opening of 2000 to 37 μm anda receiving plate to a Ro-tap machine, manufactured by Heiko Seisakusho,with the tapping number: 156/min. and rolling number: 290/min.,vibrating 100 g of a sample therein for 10 minutes to sieve it andcalculating a median diameter from the obtained weight fractions withsieve sizes, respectively. When the median diameter obtained with theJIS K 8801 standard sieve is 50 μm or less, calculation may be made froman average value of Feret's diameter with a scanning electronmicroscope.

The concentration of α-amylase, in terms of a percent by weight ofenzyme protein, is preferably 0.1 to 20%. The enzyme protein wasquantified according to the Lowry method (Lowry, O. H. et al., J. Biol.Chem., 193, 265 (1951)) and expressed by using bovine serum albumin(BSA) (product number: A-7030, manufactured by SIGMA) as standard.

The oxidizing agent used in the present invention is not particularlylimited insofar as it is solid, and can be used in any forms such aspowder, granules, and granulated particles. The oxidizing agent includesat least one member selected from percarbonate, perborate, persulfate,permanganate, and perchlorate.

Specifically, sodium percarbonate, sodium perborate, a sodiumtartrate/hydrogen peroxide adduct, a urea/hydrogen peroxide adduct, asodium tripolyphosphate/hydrogen peroxide adduct, a sodiumpyrophosphate/hydrogen peroxide adduct, a 4Na₂SO₄.2H₂O₂/NaCl doublesalt, sodium peroxide, calcium peroxide, sodium persulfate, potassiumpersulfate, ammonium persulfate, their mixture forming sulfate ionradicals, potassium permanganate, sodium perchlorate, sodiumhypochlorite etc.

In consideration of safety and easy handling for use, preferable amongthose described above are sodium percarbonate, sodium perborate, andsodium perchlorate. These oxidizing agents can be used alone or as amixture of two or more thereof. The percarbonate which can be used iscommercially available from Wako Pure Chemical Industries, Ltd.,Mitsubishi Gas Chemical Company, Inc., Nippon Peroxide Co., Ltd., andAsahi Denka Kogyo K.K.; the perborate which can be used is availablefrom Wako Pure Chemical Industries, Ltd., Mitsubishi Gas ChemicalCompany, Inc., Degussa-Huels Co., and Shaoxing Sino-USA (Meihua) HomeSolution Co., Ltd.; and the perchlorate which can be used is availablefrom Wako Pure Chemical Industries, Ltd., Mitsubishi Gas ChemicalCompany, Inc., etc. The oxidizing agent is preferably in the form ofparticles having an average particle diameter of 40 to 4000 μm,particularly 100 to 1500 μm.

Preferably, 1 IU (international unit) to 5 hundred million IU,especially 100 IU to 50 million IU, of α-amylase is contacted with theoxidizing agent in an amount corresponding to 1 g effective oxygen.

The activity of α-amylase is measured by a phadebas method illustratedin the Examples below.

The amount of effective oxygen in the oxidizing agent can be determinedby the following iodometric method.

(Method of Measuring the Amount of Effective Oxygen)

The oxidizing agent is dissolved in 0.5% aqueous sulfuric acid, 10 ml ofthe resulting solution is sampled in a glass bottle with a cap(manufactured by Maruemu Co., Ltd.), 10 ml of 20 wt % aqueous sulfuricacid is added, then 10 ml of 10 wt % potassium iodide is added, and thesample is sealed and left at 40° C. for a predetermined time in thedark. Then, this sample is left, cooled to room temperature (25° C.) andtitrated with a sodium thiosulfate standard. The amount of effectiveoxygen per g of the sample, defined by the equation (1) shown below, ismeasured. The period of time for which the sample is left untiltitration with the sodium thiosulfate standard is in such a range thatthe change in the amount of effective oxygen is within ±10%.Amount of effective oxygen per g of the sample=[(N×T/1000)×F×½×16]/X  (1)

-   X: Amount (g) of the oxidizing agent sample;-   N: Normal of sodium thiosulfate;-   T: Titration amount (ml) of sodium thiosulfate; and-   F: Factor of sodium thiosulfate.

The time for which α-amylase is contacted with the oxidizing agent ispreferably 10 seconds or more, more preferably 5 minutes to 2 months.

The temperature at which α-amylase is contacted with the oxidizing agentis preferably 5 to 80° C., more preferably 20 to 50° C. This temperatureis the ambient temperature of the two components.

The absolute humidity under which α-amylase is contacted with theoxidizing agent is preferably 0.5 to 1000 g/m³, more preferably 1.5 to200 g/m³. This humidity is the ambient humidity of the two components.

After α-amylase or particles containing the same are contacted with theoxidizing agent or particles containing the same, known methods can beused to separate them from each other. Such methods include, forexample, a method of separating them depending on a difference inoutward appearance, a method of separating them depending on adifference in particle diameter or absolute specific gravity. The lattermethod includes screening and air classification, and this screeningincludes vibrating screening, and the air classification includesdynamic, inertial, or centrifugal classification. The method ofseparation by a vibrating screen is preferable for easiness inoperation. A vibrating sieve(model 502), sold by Dalton Co. ,Ltd. andGyroshifter(model GS-132-25·AM) manufactured by Tokuju KousakushoCo.,Ltd. may be specifically used.

Particularly, the particle diameter distribution of α-amylase orparticles containing the same is preferably different from that of theoxidizing agent or particles containing the same to such an extent thatα-amylase can be sufficiently separated or recovered by screening or thelike, and usually separation and recovery can be achieved when the twoare sufficiently different from each other in average particle diameter.The difference between the minimum particle diameter of one particlegroup and the maximum particle diameter of the other particle group isfor example preferably 1 μm or more.

The contacting is achieved by mixing α-amylase or particles containingthe same with the oxidizing agent or particles containing the same, andwhen particles such as granulated particles are used, those having theabove-mentioned particle diameter can be used to exhibit the same effectas achieved by directly mixing the two, regardless of the distribution(concentration distribution) of α-amylase or the oxidizing agent in theparticles.

A detergent composition containing the α-amylase obtained according tothe activation method described above has higher detergency than that ofa composition containing untreated α-amylase.

In the present invention, a detergent composition can be produced bymixing and contacting A) α-amylase or particles containing the same withB) an oxidizing agent or particles containing the same, and thenincorporating them in a mixed state without separation into a detergentbase. The method of mixing and treating the component A) with thecomponent B) includes a method of using a mixer used in production of adetergent composition, for example a container-rotating mixer such as acylindrical mixer and V blender or a container-fixed mixer such as aribbon mixer. As the detergent base, known detergent bases obtained by atypical process for producing a detergent composition, such as aspray-drying method, a dry neutralization method, a dry granulationmethod, an agitating granulation method, a milling granulation method ora wet granulation method can be used.

EXAMPLES

The following examples further describe and demonstrate embodiments ofthe present invention. The examples are given solely for the purpose ofillustration and are not to be construed as limitations of the presentinvention.

Hereinafter, the method (phadebas method) used to measure the activityof α-amylase in the Examples is described.

<Method for Measuring the Activity of α-Amylase>

(1) Measurement of the Absorbance of a Sample

One tablet from Neo, Amylase Test “Daiichi” (product number: 701501-005,available from Daiichi Pure Chemicals Co., Ltd.) was added to 5 mLbuffer (Britton-Robinson's Buffer, pH 8.5, 50 mM (Koichi Anan et al.,Fundamental Biochemical Experimental Method 6 [in Japanese], p. 277,Maruzen Co., Ltd.)) and stirred for about 10 seconds, then 1 mL enzymesolution diluted with 2 mM aqueous calcium chloride was added, and themixture was reacted at 50° C. for 15 minutes. 1 mL of 0.5 N aqueoussodium hydroxide was added to the solution under stirring to terminatethe reaction, and then the reaction solution was centrifuged (400×g, 5minutes) to precipitate insoluble components, and the supernatant thusobtained by centrifugation was measured for absorbance at 620 nm.

(2) Measurement of the Absorbance of a Blank

One tablet from Neo, Amylase Test “Daiichi” was added to 5 mL buffer(Britton-Robinson's Buffer, pH 8.5, 50 mM (Koichi Anan et al.,Fundamental Biochemical Experimental Method 6 [in Japanese], p. 277,Maruzen Co., Ltd.)) and stirred for about 10 seconds. 1 mL of 0.5 Naqueous sodium hydroxide was added and stirred, then 1 mL enzymesolution was added, and the mixture was incubated at 50° C. for 15minutes and centrifuged (400×g, 5 minutes). The supernatant thusobtained by centrifugation was measured for absorbance at 620 nm.

(3) Calculation of Enzyme Activity

The activity of amylase was calculated from the difference in absorbancebetween (1) and (2) in a calibration curve as a standard of anInternational Unit sample enclosed with Neo, Amylase Test “Daiichi”.

Example 1

(1) α-Amylase and Oxidizing Agent

Duramyl 60T (α-amylase) commercially available from Novozymes A/S wassieved to give Duramyl 60T with a large particle diameter [(a1), averageparticle diameter (median diameter): 709 μm] from a fraction remainingon JIS standard 500 μm sieve. A percarbonate-based oxidizing agent SPC-Davailable from Mitsubishi Gas Chemical Company, Inc. was milled in amortar to give oxidizing agent powder with a small particle diameter[(b1), average particle diameter (median diameter): 281 μm] from afraction passing through JIS standard 500 μm sieve. 1 g of thisoxidizing agent SPC-D (b1) expressed in terms of the amount of effectiveoxygen, was 0.12 g, and the enzyme activity of Duramyl 60T before thecontacting step was 12000 IU/g. The median diameter is the diameter ofparticles corresponding to 50% in a distribution curve on the sieve.

(2) Mixing Ratio

3.0 g of Duramyl 60T (a1) and the oxidizing agent powder (b1) preparedin (1) above were mixed in weight ratios (enzyme/oxidizing agent) of100/1, 10/1 and 1/10 in glass bottles (No. 3, manufactured by MaruemuCorporation) respectively, then capped, and contacted with each other at25° C. and absolute humidity: 8 g/m³ for 30 minutes. These mixtures wereseparated by JIS standard 500 μm sieve to recover Duramyl 60T (a1) afterthe contacting step. When the enzyme activity of the separated Duramyl60T was measured by the method described above, the present products hada higher enzyme activity than that of the enzyme (control) not contactedwith the oxidizing agent (Table 1). TABLE 1 ratio by weight Relative(enzyme/oxidizing agent) activity (%)* 100/1  133 10/1  150  1/10 201*Relative activity: Enzyme activity relative to the enzyme activity [=100%] of the enzyme (control) not contacted with the oxidizing agent.(3) Contact Time

3.0 g of Duramyl 60T (a1) and 0.3 g of the oxidizing agent powder (b1)prepared in (1) above were mixed in a weight ratio (enzyme/oxidizingagent) of 10/1 in glass bottles (No. 3, manufactured by MaruemuCorporation), then capped, and contacted with each other at 25° C. andabsolute humidity: 8 g/m³ for 30 seconds, 5 minutes, 30 minutes, 3 daysand 50 days respectively (indicated as “closed” in Table 2). Thesemixtures were separated by JIS standard 500 μm sieve. When the enzymeactivity of the separated Duramyl 60T was measured by the methoddescribed above, the present products had a higher enzyme activity thanthat of the enzyme (control) not contacted with the oxidizing agent(Table 2).

(4) Temperature

3.0 g of Duramyl 60T (a1) and 0.3 g of the oxidizing agent powder (b1)prepared in (1) above were mixed in a weight ratio (enzyme/oxidizingagent) of 10/1 in glass bottles (No. 3, manufactured by MaruemuCorporation), then capped, and contacted with each other at 50° C. andabsolute humidity: 8 g/m³ for 30 minutes (indicated as “closed” in Table2). These mixtures were separated by JIS standard 500 μm sieve. When theenzyme activity of the separated Duramyl 60T was measured by the methoddescribed above, the present products had a higher enzyme activity thanthat of the enzyme (control) not contacted with the oxidizing agent(Table 2).

(5) Humidity

3.0 g of Duramyl 60T (a1) and 0.3 g of the oxidizing agent powder (b1)prepared in (1) above were mixed in a weight ratio (enzyme/oxidizingagent) of 10/1 in glass bottles (No. 3, manufactured by MaruemuCorporation) and contacted with each other at 20° C. and absolutehumidity: 11.2 g/m³ for 60 minutes without capping. These mixtures wereseparated by JIS standard 500 μm sieve. When the enzyme activity of theseparated Duramyl 60T was measured by the method described above, thepresent products had a higher enzyme activity than that of the enzyme(control) not contacted with the oxidizing agent (Table 2). TABLE 2Contact Contact absolute temperature humidity Contact time Relativeactivity (%) 25° C. 8 g/m³ 30 seconds 136 5 minutes 130 30 minutes 150 3days 170 50 days 153 50° C. 8 g/m³ 30 minutes 159 20° C. 11.2 g/m³ 60minutes 120*Contact ratio:Weight ratio of 10/1 (enzyme/oxidizing agent)(6) Types of Oxidizing Agents

Oxidizing agent powders (b2) with a small particle diameter wereobtained from passing fractions, through JIS standard 500 μm sieve, ofsodium perborate.4H₂O (product number 28-3630-5, manufactured by WakoPure Chemical Industries, Ltd.) and sodium perchlorate.1H₂O (productnumber 193-08065, manufactured by Wako Pure Chemical Industries, Ltd.)respectively. The amount of effective oxygen in 1 g of each kind ofoxidizing agent was 0.12 g in the case of sodium perborate.4H₂O or 0.03g in the case of sodium perchlorate.1H₂O. 3.0 g of Duramyl 60T (a1)prepared in (1) above and 0.3 g of the oxidizing agent powder (b2) weremixed in a weight ratio (enzyme/oxidizing agent) of 10/1 in glassbottles (No. 3, manufactured by Maruemu Corporation), then capped, andcontacted with each other at 25° C. and absolute humidity: 8 g/m³ for 30minutes. These mixtures were separated by JIS standard 500 μm sieve.When the enzyme activity of the separated Duramyl 60T was measured bythe method described above, the present products had a higher enzymeactivity than that of the enzyme (control) not contacted with theoxidizing agent (Table 3). TABLE 3 Relative activity Oxidizing agent (%)Sodium perborate-4H₂O 140 Sodium perchlorate-1H₂O 120*Contact ratio:Weight ratio of 10/1 (enzyme/oxidizing agent)(7) Particle Diameter of the Oxidizing Agent

3.0 g of a passing fraction, through JIS standard 500 μm sieve, ofDuramyl 60T (a1) [(a2), average particle diameter (median diameter): 380μm] and 0.3 g of a fraction of non-milled SPC-D remaining on JISstandard 500 μm sieve [(b3), average particle diameter (median diameter)879 μm, indicated as “Not milled” in Table 4] were mixed in a weightratio (enzyme/oxidizing agent) of 10/1 in glass bottles (No. 3,manufactured by Maruemu Corporation), then capped, and contacted witheach other at 25° C. at 8 g/m³ for 30 minutes. These mixtures wereseparated by JIS standard 500 μm sieve. Separately, Duramyl 60T (a1) andthe oxidizing agent powder with a small particle diameter [indicated as“Milled” in the table] obtained from a fraction passing through JISstandard 500 μm sieve were treated in the same manner as describedabove. When the enzyme activity of the separated Duramyl 60T wasmeasured by the method described above, the present products regardlessof the particle diameter of the oxidizing agent had a higher enzymeactivity than that of the enzyme (control) not contacted with theoxidizing agent (Table 4). TABLE 4 Form of oxidizing Relative activityUsed enzyme agent (%) (a1) Milled 150 (a2) Not milled 148*Contact ratio:weight ratio of 10/1 (enzyme/oxidizing agent)(8) Activation of α-Amylase by Using the Recovered Oxidizing Agent

When the oxidizing agent after contacting, used in (2) in Example 1, wasrecovered and then contacted by the method in (2) above with Duramyl 60T(a1) [prepared in (1) above) not contacted with the oxidizing agent, theproduct of the present invention had a higher enzyme activity than theenzyme (control) not contacted with the oxidizing agent.

(9) Enzyme After Separation

The enzyme separated from the oxidizing agent powder (b1) in (3) inExample 1 was placed in glass bottles (No. 3, manufactured by MaruemuCorporation), then capped, and stored at 25° C. and absolute humidity: 8g/m³ for 30 days. When the enzyme activity of Duramyl 60T was measuredby the method described above, the enzyme had a high activity even afterstorage.

Example 2

When Termamyl 60T or Stainzyme 12T commercially available from NovozymesA/S was treated in the same manner as in (1), (3) and (5) in Example 1and measured for α-amylase activity, the present products had a higheractivity than that of the enzyme (control) not contacted with theoxidizing agent (Table 5). The enzyme activities of Termamyl 60T [(a3),average particle diameter (median diameter) : 700 μm] and Stainzyme 12T[(a4), average particle diameter (median diameter): 652 μm] before thecontacting step were 10000 IU/g and 180000 IU/g, respectively. TABLE 5Contact Contact Relative activity (%) tempera- absolute Contact TermamylStainzyme ture humidity time 60T (a3) 12T (a4) 25° C.  8 g/m³  5 minutes110 110  8 g/m³ 30 minutes 120 120 40° C. 43 g/m³ 30 minutes 120 137*Contact ratio:weight ratio of 10/1 (enzyme/oxidizing agent)

Example 3

When Purastar OxAm commercially available from Genencor InternationalInc. was treated in the same manner as in (1), (3), (4) and (5) inExample 1 and measured for α-amylase activity, the present products hada higher activity than that of the enzyme (control) not contacted withthe oxidizing agent (Table 5). The enzyme activity of Purastar OxAm(Purastar OxAm) [(a5), average particle diameter (median diameter): 679μm] before the contacting step was 37000 IU/g. TABLE 6 Contact Contactabsolute temperature humidity Contact time Relative activity (%) 25° C.8 g/m³ 5 minutes 120 30 minutes 120 3 days 135 50° C. 8 g/m³ 30 minutes121 40° C. 43 g/m³ 30 minutes 145*Contact ratio:weight ratio of 10/1 (enzyme/oxidizing agent)

Example 4

0.5 wt % Duramyl 60T (a1) contacted with the oxidizing agent (weightratio of 10/1 (enzyme/oxidizing agent)) in Example 1, and 0.5 wt %perfume, were incorporated into 99 wt % detergent base described inExample 3 in WO99/29830, to give a detergent composition A. Separately,a detergent composition B was obtained by incorporation of 0.5 wt %Duramyl 60T (a1) not treated with the oxidizing agent, in place of theabove Duramyl 60T (a1).

The detergent composition A or B was dissolved at a concentration foruse (concentration of 1 wt %) in 1 L tap water regulated at 30° C., andthen transferred to a stainless beaker for Terg-O-Tometer (manufacturedby Ueshima Seisakusho Co., Ltd.). Starch/dye-stained five clothes(EMPA162) (6 cm×6 cm) were placed in the resulting detergent solution,stirred and washed at 80 rpm for 10 minutes. After washing with runningwater, the clothes were pressed and measured for their reflectance. Thereflectance of a raw cloth used to prepare the stained cloth, and thereflectance of the artificially stained cloth before and after washing,were measured at 460 nm with an automatic color difference meter(Shimadzu Corporation) to determine the degree of washing (%). As aresult, it was confirmed that the detergent composition A had higherdetergency than that of the detergent composition B.

Example 5

(1) Preparation of Stained Dishes

China plates of 25 cm in diameter were boiled in boiling tap water, andsoft cooked rice was left for 30 minutes at room temperature (25° C.),and then 3 g of the rice was spread over each of the China plates, driedat room temperature for about 3 hours, and stored (in a semi-sealedstate) at 5° C. just before use.

(2) Washing Conditions

The contaminated dishes were washed under the following conditions.Three stained dishes were washed each time.

-   Used machine: Automatic dish washer NP-810 manufactured by    Matsushita Electronic Industry Co., Ltd.-   Washing temperature: Gradual increase in temperature from water    temperature to about 55° C.-   Washing water: tap water (ca.4° DH)-   Detergent concentration: 0.2 wt %.-   Washing time: washing for about 20 minutes→rinsing for about 20    minutes (standard course)-   Amount of circulating water during washing: 3.5 L.

Used detergent compositions: shown in Table 7. TABLE 7 Detergentcomposition Detergent composition Component C D Pluronic L-61¹⁾ — —Softanol EP-7085²⁾ 4.0 4.0 Trisodium citrate — — Sodium tripolyphosphate30.0 30.0 Sodium percarbonate 20.0 20.0 Sodium carbonate 10.0 10.0Amorphorous silicate³⁾ 4.0 4.0 AA-MA⁴⁾ 10.0 10.0 Sodium sulfate 1.0 1.0Activated α-amylase⁵⁾ 1.0 Untreated α-amylase⁶⁾ — 1.0

1) Polyoxyethylene/polyoxypropylene copolymer (weight-average molecularweight 2,000, manufactured by Asahi Denka Kogyo K.K.)

2) A C12 to C14 sec-alcohol adduct having 7 moles on average of ethyleneoxide and 8.5 moles on average of propylene oxide added thereto (randomadduct)

3) Sodium silicate JIS No. 2

4) An acrylic acid/maleic acid copolymer (acrylic acid/maleic acid=70/30 molar ratio, weight-average molecular weight 6000)

5) Duramyl 60T (a1) used in Example 4 [after treatment in a weight ratioof 10/1 (enzyme/oxidizing agent) in Example 1]

6) Duramyl 60T (a1) (control) not treated with the oxidizing agent

After the wash, each soiled plate was dyed with 5 ml of 5 mmol/L iodinesolution, which had been obtained by diluting 0.05 mol/L iodine solution(product number 15-0620-5, manufactured by SIGMA-ALDRICH, Inc.) by 10%with ion-exchange water. Their washing performances were compared byvisual judgment. As a result, the detergent composition C containingactivated α-amylase had extremely higher detergency than that of thedetergent composition D containing untreated α-amylase.

Example 6

0.5 wt % activation-treated mixture of Duramyl 60T (a1) and oxidizingagent powder (b1) [weight ratio of 10/1 (enzyme/oxidizing agent), notseparated from each other] prepared in the item of mixing ratio in (2)in Example 1 and 0.5 wt % perfume were incorporated into 99 wt %detergent base described in Example 3 in WO99/29830, to give a detergentcomposition E. As control, a detergent composition F was obtained byincorporation of 0.455 wt % Duramyl 60T (a1) not treated with theoxidizing agent, 0.045 wt % oxidizing agent powder (b1), and 0.5 wt %perfume into 99 wt % of the same detergent base.

As a result of the comparison of detergency between the two detergentcompositions by the detergency method described in Example 4, it wasconfirmed that the detergent composition E had higher detergency thanthat of the detergent composition F.

1. A method of activating α-amylase, which comprises a step ofcontacting A) α-amylase or particles comprising α-amylase with B) anoxidizing agent or particles comprising an oxidizing agent.
 2. A methodof activating α-amylase, which comprises steps of contacting A)α-amylase or particles comprising α-amylase with B) an oxidizing agentor particles comprising an oxidizing agent and separating A) α-amylaseor particles comprising α-amylase after the contacting step.
 3. A methodof producing activated α-amylase, which comprises steps of contacting A)α-amylase or particles comprising α-amylase with B) an oxidizing agentor particles comprising an oxidizing agent and separating A) α-amylaseor particles comprising α-amylase after the contacting step.
 4. Themethod according to any one of claims 1 to 3, wherein the component A)is contacted with the component B) for 30 seconds or longer.
 5. Themethod according to any one of claims 1 to 3, wherein the oxidizingagent is at least one selected from the group consisting ofpercarbonate, perborate, persulfate, perchlorate, and permanganate. 6.The method according to any one of claims 1 to 3, wherein one to fivehundred million IU (international unit) of α-amylase is contacted withthe oxidizing agent in an amount corresponding to 1 g of effectiveoxygen.
 7. α-Amylase which is obtainable by the method according to anyone of claims 1 to
 3. 8. A detergent composition comprising theα-amylase which is obtainable by the method according to any one ofclaims 1 to
 3. 9. A method of producing an α-amylase-containingdetergent composition, which comprises mixing a detergent base with amixed and treated material obtained by mixing A) α-amylase or particlescomprising α-amylase with B) an oxidizing agent or particles comprisingan oxidizing agent.